1. Field of the Invention
The present invention relates to a semiconductor unit, and a power conversion system and an on-vehicle electrical system using the same.
2. Description of the Related Art
For semiconductor devices, particularly, for power semiconductor devices that switch large currents, double-side cooling semiconductor unites that cool the power semiconductor devices from both sides are being contemplated because of the high heating values. The performance needed to cool semiconductor devices depends on the environments of electrical systems to which an electric circuit module equipped with the semiconductor devices is to be mounted. For example, power conversion systems for vehicles require high performance to cool the electrical systems because of the on-vehicle environment and operating environment.
An example of conventional double-side cooling semiconductor units is disclosed in JP-A-2004-296663, which is constructed of a first radiator of H-shaped cross section, first and second semiconductor devices disposed in first and second recesses of the H-shaped first radiator, respectively, and second and third radiators mounted to the upper surfaces of the first and second semiconductor devices, respectively. Thus, the lower surfaces of the semiconductor devices radiate heat from the first radiator, while the upper surfaces of the semiconductor devices radiate heat from the second and third radiators to enable double-side cooling.